This invention pertains to the art of closure devices and methods for making closure devices and, more particularly, to such devices and their manufacture used in covering and sealing openings or apertures formed in thin plates, rigid sheets of metal, or other materials.
The invention is particularly applicable to the type of closure plugs used for covering openings in motor vehicle body panels and will be described with particular reference thereto. It is to be appreciated, however, that the invention has broader applications and may advantageously be employed for other uses in a variety of different environments whenever it is necessary to cover and seal an opening in a support panel.
In the manufacture of motor vehicles, closure devices are used to permanently close various body panel apertures or access openings which have served their intended purpose and are no longer required, or to perform some other useful function such as to reduce the effective diameter of an opening to a desired new size or to provide a suitable mounting surface for another component. Such openings may be required initially for many reasons, e.g., as paint discharge openings or access openings to accommodate mounting of vehicle components. It is typically required that these discharge or access apertures be tightly covered and sealed after they have served their useful function in order to prevent moisture, road dirt, noise, exhaust fumes, and the like from entering into the motor vehicle through the panel aperture.
Conventional closure devices that provide a fluid-tight seal have heretofore included a main body portion attached to a separate sealing ring made from a material different than that comprising the body of the closure device. The main body portion of the conventional closure devices are typically formed of a durable metal material or a resilient synthetic or plastic material to ensure the mechanical integrity of the closure device. The sealing rings, however, are often formed from soft materials such as extruded rubberized compounds or heat sealable materials. During the manufacture of such conventional closure devices, much time and effort is consumed in first extruding and die cutting the sealing rings and then in mounting the separate sealing rings onto the body of the closure devices such as by a mechanical connection, or by using adhesives or the like. Often, the sealing rings are attached to the plug bodies by hand. Such arrangement and practice is disadvantageous because of the additional cost and labor investment required.
Two-shot molding techniques have been used in the past to mold various components from two different materials. As an example, two-shot molding can be used to form parts having two different colors or to form parts having two different hardness regions. However, two-shot molding techniques have heretofore been unsuccessful in producing parts formed of a rigid plastic together with a thermoexpandable material due mainly to an inability to control the temperature of the molding dies.
It has, therefore, been considered desirable to develop a new and improved closure device and assembly and method for making same which overcomes the foregoing deficiencies and others while providing better and more effective operation of results.